Firefox search engine settings keep resetting
I use Firefox on a Macbook.
I configured the search (about:preferences#search) to include only one search engine: DDG. As a result, when the URL/search bar is focused, the bottom bar with "This time, search with..." is not displayed. This is the expected behavior.
Starting about a month ago, it started exhibiting a bug: at random times, the search settings are getting reset. So whenever I open a new tab and focus the URL/search bar, the bottom bar with "This time, search with..." is appearing and displays four icons. When I go to search preferences, I see the same search engines that I removed a while ago.
This pattern has repeated about five times, and I'm getting tired of it. Is there a way I can make sure that Firefox remembers my preferences and doesn't reset them?
Thank you, Alex