(I am not a security expert either)

But, one of the arguments that I saw online from this was that when a security researcher finds a bug and reports it to the OSS project/Company they then fix the code silently and include it within the new version and after some time, they make the information public

So if you run infrequently updated versions, then you run a risk of allowing hackers access as well.

(An good example I can think of is OpenCode which had an issue which could allow RCE and the security researcher team asked Opencode secretly but no response came so after sometime of no response, they released the knowledge in public and Opencode quickly made a patch to fix that issue but if you were running the older code, you would've been vulnerable to RCE)