flóri 
@Lizette603_23 from a quick glance at the mastodon website, the following filter should work:
this will hide all posts that have an image attachment without alt text
note that if mastodon devs change the layout of the page, this might stop working
this filter is written for uBlock Origin, which is an ad blocker
to add the filter, click on the addon's icon, then open the dashboard (three cogs icon), then go to the "My filters" tab, paste it in, and click save
##.status:has(.media-gallery__item-thumbnail img:not([alt]))this will hide all posts that have an image attachment without alt text
note that if mastodon devs change the layout of the page, this might stop working
this filter is written for uBlock Origin, which is an ad blocker
to add the filter, click on the addon's icon, then open the dashboard (three cogs icon), then go to the "My filters" tab, paste it in, and click save
