Hi @Kinasz, Mateus,
I'm glad to hear you solve the problem ,if you have any issue about SharePoint, you are welcome to raise a ticket in this forum.
By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others." and according to the scenario introduced here: Answering your own questions on Microsoft Q&A, I would make a brief summary of this thread:
[SharePoint REST API endpoint filter]
unable to combine the two querytext. Also tried using filter with different syntaxes, but still doesn't work.
Fixed by using 'refinementfilters'. Could refer to following query
You could click the "Accept Answer" button for this summary to close this thread, and this can make it easier for other community member's to see the useful information when reading this thread. Thanks for your understanding!