OK, I tried it for myself.
When I put this code (without spaces and linebreaks) in DHTML or Koivi:
le="color: #000000"><?php [ url=https://xoops.org/modules/news/] [ img]https://xoops.org/modules/news/images/topics/xoops.gif[ /img] [ /url] [ url=https://xoops.org/modules/news/] [ img]https://xoops.org/modules/news/images/topics/xoops.gif[ /img] [ /url]
then I get this html source in the preview:
le="color: #000000"><?php <table class="outer" width="98%" cellpadding="4" cellspacing="1"> <tbody><tr><td class="head">test</td></tr> <tr><td> <br> <a href="https://xoops.org/modules/news/" target="_blank"> <img src="https://xoops.org/modules/news/images/topics/xoops.gif" alt=""> </a> <a href="https://xoops.org/modules/news/" target="_blank"> <img src="https://xoops.org/modules/news/images/topics/xoops.gif" alt=""> </a> <br> </td></tr></tbody></table>
The images are nicely tiled one after the other on the same row.
After posting, I get the same result as you. This is the resulting html source:
le="color: #000000"><?php <table class="outer" width="98%" cellpadding="4" cellspacing="1"> <tbody><tr><td class="head">test</td></tr> <tr><td> <br> <a target="_blank" href="https://xoops.org/modules/news/" rel="external"> </a> <a href='javascript:CaricaFoto("https://xoops.org/modules/news/images/topics/xoops.gif");'> <img src="https://xoops.org/modules/news/images/topics/xoops.gif" alt="Open in new window" onload="JavaScript:imageResize(this, 300)" border="0"> </a> <br> <a target="_blank" href="https://xoops.org/modules/news/" rel="external"> </a> <a href='javascript:CaricaFoto("https://xoops.org/modules/news/images/topics/xoops.gif");'> <img src="https://xoops.org/modules/news/images/topics/xoops.gif" alt="Open in new window" onload="JavaScript:imageResize(this, 300)" border="0"> </a> <br><br> </td></tr></tbody></table>
The images are positioned one under the other, due to the insert of an unwanted <br>. Also the required links are useless.
I think this can't be the intention of the BBcode translation and consider it as a bug.
On this forum, you can see the result:
(Clicking on the images is supposed to open the news section)


When the BBcodes are put in a code block then they translate to html source. Should the code block not prevent this?
le="color: #000000"><?php [url=https://xoops.org/modules/news/][img]https://xoops.org/modules/news/images/topics/xoops.gif[/img][/url][url=https://xoops.org/modules/news/][img]https://xoops.org/modules/news/images/topics/xoops.gif[/img][/url]