C7 v3, 21.02.0-snapshot, OOM reaper after a few days of good behavior

My C7, being used as an AP, with a mini x86 box separately doing the routing duty. Home system, about 23 stations connected, not huge amounts of data. This is the snapshot not the release version, openwrt-21.02-snapshot-r16297-1c95d78f08-ath79-generic-tplink_archer-c7-v2-squashfs-sysupgrade.bin, from about 9-30-21.

Things had been doing well after the changeover from 19.07.8, excepting the occasional and ongoing 2.4ghz radio dropouts (see other threads). About 4 days uptime now, and there was a sudden drop and return of the 5ghz radio. Checking the logs, I see a OOM reaper event, and 3-4 more processes killed, with finally both radios and the eth ports going offline, and coming back. Seemed the ath10k driver was reloaded.

I don't know how to go about troubleshooting this, any help appriciated. Below is the first event, I could add more from the syslog, if that would help.

[135549.215159] CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.4.143 #0
[135549.222583] Stack : 00000240 800b95d8 80660000 805fa440 00000000 00000000 00000000 00000000
[135549.231204]         00000000 00000000 00000000 00000000 00000000 00000001 87c3dc18 bbd8d794
[135549.241322]         87c3dcb0 00000000 00000000 000000ed 00000038 8057a304 20352e34 2e313433
[135549.251301]         000000ed 57f26d68 00000000 6b746872 00000000 87c3dbf8 87e130c0 00000200
[135549.261203]         00000000 8065e8cc 00000007 00400dc0 00000003 8031fd68 00000000 80790000
[135549.272048]         ...
[135549.275896] Call Trace:
[135549.275913] [<800b95d8>] 0x800b95d8
[135549.283493] [<80660000>] 0x80660000
[135549.288326] [<8057a304>] 0x8057a304
[135549.293145] [<8031fd68>] 0x8031fd68
[135549.298037] [<80069364>] 0x80069364
[135549.303011] [<8006936c>] 0x8006936c
[135549.309383] [<8012e53c>] 0x8012e53c
[135549.314366] [<8012efd8>] 0x8012efd8
[135549.319327] [<80150c8c>] 0x80150c8c
[135549.324341] [<8012f78c>] 0x8012f78c
[135549.330635] [<8016f360>] 0x8016f360
[135549.334271] [<8007fc44>] 0x8007fc44
[135549.339333] [<800aaf1c>] 0x800aaf1c
[135549.344263] [<800aa724>] 0x800aa724
[135549.349187] [<8009e750>] 0x8009e750
[135549.355588] [<80081030>] 0x80081030
[135549.360665] [<8009e750>] 0x8009e750
[135549.365613] [<8008122c>] 0x8008122c
[135549.369288] [<8009e750>] 0x8009e750
[135549.374241] [<8009fcf8>] 0x8009fcf8
[135549.379333] [<8009fc20>] 0x8009fc20
[135549.384388] [<8009fc20>] 0x8009fc20
[135549.388061] [<80064bf8>] 0x80064bf8
[135549.393148] 
[135549.394799] Mem-Info:
[135549.398445] active_anon:627 inactive_anon:4 isolated_anon:0
[135549.398445]  active_file:2 inactive_file:5 isolated_file:0
[135549.398445]  unevictable:0 dirty:0 writeback:0 unstable:0
[135549.398445]  slab_reclaimable:333 slab_unreclaimable:6567
[135549.398445]  mapped:2 shmem:53 pagetables:58 bounce:0
[135549.398445]  free:4015 free_pcp:4 free_cma:0
[135549.432324] Node 0 active_anon:2508kB inactive_anon:16kB active_file:8kB inactive_file:20kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:8kB dirty:0kB writeback:0kB shmem:212kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
[135549.456018] Normal free:16148kB min:16384kB low:20480kB high:24576kB active_anon:2508kB inactive_anon:16kB active_file:8kB inactive_file:20kB unevictable:0kB writepending:0kB present:131072kB managed:123400kB mlocked:0kB kernel_stack:328kB pagetables:232kB bounce:0kB free_pcp:16kB local_pcp:16kB free_cma:0kB
[135549.485572] lowmem_reserve[]: 0 0
[135549.490653] Normal: 413*4kB (UM) 218*8kB (UM) 139*16kB (UM) 54*32kB (UM) 27*64kB (M) 10*128kB (UM) 5*256kB (M) 5*512kB (UM) 2*1024kB (M) 0*2048kB 0*4096kB = 16244kB
[135549.507322] 60 total pagecache pages
[135549.512677] 0 pages in swap cache
[135549.517551] Swap cache stats: add 0, delete 0, find 0/0
[135549.524614] Free swap  = 0kB
[135549.530436] Total swap = 0kB
[135549.534961] 32768 pages RAM
[135549.537886] 0 pages HighMem/MovableOnly
[135549.543443] 1918 pages reserved
[135549.546764] Tasks state (memory values in pages):
[135549.553170] [  pid  ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name
[135549.562055] [    639]    81   639      326       27    20480        0             0 ubusd
[135549.570449] [    640]     0   640      235        9    12288        0             0 askfirst
[135549.580659] [    674]     0   674      261       12    16384        0             0 urngd
[135549.590394] [   1149]   514  1149      327       44    20480        0             0 logd
[135549.598739] [   1218]     0  1218      607      135    20480        0             0 rpcd
[135549.608446] [   1292]     0  1292      287       11    12288        0             0 dropbear
[135549.618701] [   1341]     0  1341      912       58    24576        0             0 hostapd
[135549.628623] [   1342]     0  1342      888       27    16384        0             0 wpa_supplicant
[135549.639340] [   1404]     0  1404      430       35    24576        0             0 netifd
[135549.649281] [   1466]     0  1466      314       11    16384        0             0 crond
[135549.659152] [   1535]     0  1535      921      178    24576        0             0 uhttpd
[135549.669046] [   2598]     0  2598      313       10    12288        0             0 ntpd
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