With GA you can choose to anonymise users IP addresses.
You can also choose to exclude IP addresses from affecting your analytics.
The question is about how these both work together...
My theory is that it would be crazy that Google has not already thought about this and that the rules will filter FIRST as it has your IP for processing - then once it detects the exclude rule it will stop.
Only once it's passed the rules it will then anonymise the IP.
Thus IP filters are absolutely fine as they are, even after turning on IP Anonymisation.
The argument is based on what I think are terrible bits of advise from places such as https://www.en.advertisercommunity.com/t5/Google-Analytics-Filters/Excluding-internal-IP-traffic-amp-anonymize-IP/td-p/885589 which are telling users to use regex... which in no way shape or form will help any different from just setting the IP to having a .0 at the end.
Does anybody else have any more plausible advise or evidence etc to show that IP Anon doesn't affect filters?