It depends? I recall being on incident response and checking for that specifically (I worked in a big java shop at the time and was responsible for stuff like this). It was alot of screaming online, but things like Spring Framework used to pull Log4J v1 (ie: not affected) and spring-boot (the modern, way more used one) used Logback (also not affected). You'd get it from like a Kafka/Elastic dependency or similar, but only if you didn't have an SLF4J handler.. like spring would ship Logback for example. Which makes me thing, in general other java shops were mostly not affected as well, given spring is basically the go-to on the java world.

Extremely legacy software wasn't affected either (log4j v1 or apache commons-logging!). Lots of automated scanners flagging the idle jar as well (when the app used Logback for example as the SLF4J implementer, but the scanner saw a transitive for the log4j jar and would scream at you - that's when I stopped caring about github vuln scans btw, it was a shitshow).

Like dont get me wrong, it was a bad vuln, but to me it seems like it was more hype machine and internet screaming than actual vulnerable applications. I do recall Minecraft was vulnerable though, that one was indeed a big target given publicly exposed servers and such.

As a percentage of websites, though, Java is far from ubiquitous. It's probably not even double digit percentages. PHP, meanwhile, is some 70% of websites. So in terms of exploit targets, this is 10x that of Log4J, maybe.

The vulnerability also required you to log arbitrary user provided strings and maybe some other precondition that I can't remember. Nothing at my workplace at the time was affected despite using log4j since user provided data was either parsed (e.g. a uuid) or private/not something we would log.