I've investigate the OpenWrt driver is from kernel, but when i try build my own OpenWrt from git repository. There is no even folder like kernel-root-drivers-net-ethernet-intel-igb. And no ways to update it in make menuconfig. Should i build package and than somehow add it into openwrt? Maybe someone already build it?
in this post i got the clear answer - openwrt igb driver version is from corresponding mainline kernel, when i download mainline kernel - i go kernel-root-drivers-net-ethernet-intel-igb, than i open config, it say's it intel 2018.
It's not clear what OpenWrt branch you are referring to, but since I'll assume master and 5.10 kernel since you are worried about 2018 code being too old for you. The newest 5.10 commit in igb seems to be 2330d46db081 ("igb: check timestamp validity") authored March 3rd 2021 and committed to the 5.10 stable March 30th 2021.
But by definition, the igb driver release date is the release date of the kernel. Which is April 21st for the current v5.10.32 kernel in OpenWrt.
Copyright statements are not code revision trackers. Don't try to put your own meaning into stuff you don't understand.
that text with the dates is a copyright header, it is just stating ownership or origin of the code, mostly there for legal reasons. It's commonly not updated frequently.
To see when the code was last modified, you need to check the git log and the commits.
If using that basic git web interface is too basic and confusing, you can use the Github interface (on the official mirror of Linux sources), for example this https://github.com/torvalds/linux/commits/master/drivers/net/ethernet/intel/igb
where you also see Intel developers doing work on it directly, just check their email, that ends with @intel.com