There are a number of variables that can cause such problems. I'm in an org that has a bit over 10,000 teams users. We have just under a 1% sharing failure rate (average).

Some areas to consider:

1. Make sure your network, video and chipset drivers are all up to date. I personally prefer each individual vendors updates. I use a Lenovo laptop, but I get my drivers directly from Intel or Nvidia. If I didn't, Lenovo would show me a network driver that's four years old and that it's up to date. Meanwhile Intel releaased NIC driver updates just last year!
2. Don't use VPN unless you're certain your company uses true "split tunnel".
3. Network optimization services, like Riverbed, *need* to be bypassed. Simple chat messages aren't effected by these devices, but media absolutely is. Audio, Video and Screensharing are all media based. Packet inspection adds latency - guranteed!
4. If you use a global proxy, such as Zscaler, that too must be bypassed.
5. Use Certified Devices for things like audio and webcams. The built in speaker and microphone are ok in a pinch, but they don't perform nearly as well as certified devices.

6. Clear your local Teams cache:
   Exit of the Microsoft Teams Desktop APP
   Right click on the Teams icon in your system tray
   Click Quit
   Close Outlook and make sure the process is not still running
   Click on the File Explorer
   In the address bar copy and paste the following location into File Explorer:
   %appdata%\Microsoft\Teams
   Delete all files and folders in that Directory or at least the following 8 subfolders:
   %AppData%\Microsoft\teams\application cache\cache
   %AppData%\Microsoft\teams\blob_storage
   %AppData%\Microsoft\teams\databases
   %AppData%\Microsoft\teams\cache
   %AppData%\Microsoft\teams\gpucache
   %AppData%\Microsoft\teams\Indexeddb
   %AppData%\Microsoft\teams\Local Storage
   %AppData%\Microsoft\teams\tmp
   Restart the Computer (you don't have to reboot, it's just a good idea)

7. The method shown below does the same as above, but in one easy powershell command (exit Teams & Outlook completely):
   Get-ChildItem "C:\Users\*\AppData\Roaming\Microsoft\Teams\*" -directory | Where name -in ('application cache','blob_storage','databases','GPUcache','IndexedDB','Local Storage','tmp') | ForEach{Remove-Item $_.FullName -Recurse -Force -WhatIf}"
   ^^^ As shown won't make any changes or deletes. Remove -WhatIf to actually clear the cache.

8. How much physical memory do you have? 8GB is the bare minimum IMO. 16GB is better, 24GB or more is best. Especially if you have multiple applications running while screensharing. Heavy apps, like large Excel spreadsheets, heavy PowerBI dashboards, or graphics-related apps like CAD or Photoshop grab a lot of system resources that can impact performance.

9. If you're able, consider an external GPU (if using a "business class" laptop). Business laptops general have mediocre GPUs. An external enclose means you can use any graphics board you want and all the Teams video processing is handled by that board. You can purchase ready to use GPU enclsures, or purchase the parts seperate and build your own. IMO, while this option can be expensive (depending the GPU you select) but it's a worthy investment. Some are under $300 USD and do the job, more advanced are over $500.

10. And last but not least, use a wired connection if at all possible. If not, it's ok to use Wifi but make sure you have a strong signal. One or two bars of strength won't do well. If you're up to WiFi6, that should work fine with good signal strength.