can I restore the tabs in safari from a time machine back up?

Due to the way safari holds all the info recovering the configuration to earlier setup is not a simple recovery.

Here is a useful article.

https://www.macobserver.com/tips/quick-tip/macos-recovering-lost-tabs-and-windows-in-safari/

I am hoping the history is not cleared and you can use the method outlined here.. history shows pretty well what pages you had open and just start a new tab and search the history for each one.

Using lots of open tabs in safari is a really bad idea.. due to the amount of RAM each page uses. Even with 16GB in the computer it slowed down and had almost no free RAM. I moved to Chrome to stop the issue. Far more efficient with RAM. I do still use safari just having a couple of pages open.

And just a note.. next time do bookmark all the tabs you use so you can easily recover them. In safari you can export bookmarks as per most browsers. And then import them to your current safari. That stops you needing to remember all the tabs.

Time Machine method

Now let me say you can reconstruct your setup prior to whatever the tech did. However this is kinda tricky. You will need a suitably formatted USB drive plugged into the computer. The recovery will be made to this disk to prevent messing up your current boot drive. I am guessing the tech has unmessed up some mixup there so you don't want to recover that as well.

This might be tricky in Catalina and later due to needing APFS so tell me what OS your running on the Mac if you need more help.

I gave some details in this thread how to rebuild a working boot disk onto a USB drive plugged into your computer.

You can select the date you wish the rebuild to match.. i.e. a few days before the tech started work. You will then boot the computer from the USB drive.. and can then bookmark all your tabs.. and export your bookmarks (and history if possible)

Then copy the file across to the internal boot drive and import it to your current safari. This is messy but much safer than trying to rebuild safari history and info.

This is a long thread and fairly old.. but should still help. It covers both migration which is useless for you.. and system restore which is the one you should use.

See https://discussions.apple.com/thread/7236090?answerId=28992389022#28992389022

Ok.. Catalina is a bit different but should still work.. the issue is more to do with speed.. if you need to go through this the hard way then my suggestion would be to buy a small USB SSD that matches the size of your Mac internal drive or larger..

This is due to APFS which is required and it is designed to work on SSD although it can work on older spinning drives performance is poor.. especially portable type slow laptop drives.

Hopefully you can recover it just using the history.

If I knew where the settings for the Safari application resided in the backup, perhaps I could restore them.

It just is not that simple.. which is why I said you needed to use System Restore and recreate the boot disk to an external drive and then use that to recover the bookmarks.

Putting files in a directory does not make them work.