spot as searxng instance is proxying all search - if what it proxies to doesn’t feel like answering (because it has seen too many queries from that instance) spot comes up short. It’s the fundamental weakness of searxng.
If you want to just solve this and move on, select a direct search provider (ddg, startpage, ecosia, qwant) - all license the bing index and can always answer. Kagi has a free-month currently if you want to check it out.
Cromite supposedly offers to add the search provider after a visit. Firefox has an easy search provider choice screen.
There also lots of others searxng instances that see less traffic if you continue to feel experimental.
Newer searxng version has introspection into failure levels for end-users to turn off engine that have a high error rate: