Flask request security on ubuntu remote server

Question

I was testing my python flask app on a remote linux server with ubuntu 20.04 running python server.py without a firewall. The following then seemed to occur.

AA.AAA.AAA.AA - - [08/Feb/2024 16:58:44] code 400, message Bad request version ('®¯]')
AA.AAA.AAA.AA - - [08/Feb/2024 16:58:44] "Gh0st­àxKS``ÃÀÀÀÄ@¼Q   H§e&§*$&g+2ö°00¬¨rc \`&ÇK7ån9n;3¬èsch¨^Ï4'J©ã0Ãh]&øÎSËA4L?2=áÄ@õ`T®¯]" HTTPStatus.BAD_REQUEST -

I've since activated my firewall. Please clarify as to whether my API keys, my app and the server are currently safe and whether I can safely transfer files between my ubuntu server and my local windows machine.