Go step by step and test.
1. Launch Safari holding the Shift key down.
Test.
2. Startup in Safe Mode https://support.apple.com/lv-lv/HT201262
Login to your account.
Test.
To exit Safe Mode, click the in the menu bar and then “Restart”.
3. If Safari doesn’t load website pages
https://support.apple.com/guide/safari/if-you-cant-open-a-website-ibrw1071/mac
4. In some cases this can happen if adware, anti-virus software or cleaner type application are installed.
To find out, run EtreCheck and post the report here.
https://etrecheck.com
Click “Free download” button,
Open Downloads folder, click on it to open, and then select ”Open”.
“Choose a problem” from the popup menu box, and then “Start EtreCheck” in the dialog.
Click “Share Report” button in the toolbar, select “Copy report” .
Paste the report when you reply.