Just laying down what happened, in case someone else encounter this.
SMF is installed in a folder. The site root and another folder contain only plain HTML pages. Discovered that the images in those did not load (the second time within about two months); last time I got this resolved somehow with image link modifications in the HTML pages.
Just found that the images were not showing up again, and could resolve this by removing the list of bots placed in htaccess (in site root) by the Botbanish mod. The images are showing again.
Now I'm just wondering why this list should be having this effects on images in simple pages in other folders...the SMF forum itself was not affected.
.htaccess in forum root should only affect forum, nothing above that. It will block IPs in the directory where it's located and any subdirectories of that directory. Never tried Botbanish mod, but it shouldn't be doing anything above the forum directory.
Thanks for answering.
As stated above the concerned htaccess is in site root, not in the SMF forum folder. It appears as if the mod is placed there automatically.
Actually, I noted this problem only because the htaccess file swelled from 6 something kb to 46 kb. Then found the list there.
I removed it manually. When I checked the mod section afterwards it showed the Botbanish mod as 'not installed'. But I did not touch it all when or after removing the bot list; I assume that I must have uninstalled some time earlier, but the list remained installed...I guess.
The proper place to ask for support for the mod is likely in its support thread:
https://www.simplemachines.org/community/index.php?topic=557143.0