If your boss doesn't want you to browse the web, where some technical content is accompanied by an avatar that the author likes, they may not be suitable as boss, or at least not for positions where it's their job to look over your shoulder and make sure you're not watching series during work time. Seems like a weird employment place if they need to check that anyway
I think the complaint is rather that you don't know when it will rear its face on third-party websites that you are visiting as part of work. Forking wouldn't help with not seeing it on other sites
(Even if I agree that the boss or customers should just get over it. It's not like they're drawing genitalia on screen and it's also easily explainable if they don't already know it themselves.)
Add a rule to your adblocker for the image, then. The main site appears to have it at `anubis.techaro.lol/.within.website/x/cmd/anubis/static/img/happy.webp?cacheBuster=v1.21.3-43-gb0fa256`, so a rule for `||*/.within.website/x/cmd/anubis/static/img/$image` ought to work for ublock origin (purely a guess regarding wildcards for domain, I've never set a rule without a domain before)
I fail to see how this particular "anime girl" and the potential for clients seeing it, could make you think that's a fair request. That seems extremely ridiculous to me.
we have customers in our offices pretty much every day, I think "no anime girls on screens" is a fair request