"If they know you're spoofing, you're not spoofing hard enough." This stupid "war against bots" is going to lead to the downfall of the Internet and effectively turn it into another walled garden where only "approved" (anti-)user agents are allowed. Don't fall for the nonsense about "AI scrapers" --- it's just a way to manufacture consent.
Idk, if bots ate hammering your server then setup rate limits. If you have content that you don't want others to have access to, don't serve it with a webserver.
Those images also used to crash all the early GUI irc and chat clients that showed inline images without size checks...