GTM and UA conflict?

Question

Google Analytics

Good day dear experts!
There is an online store.
Through GTM, Y.Metrika (YM) - U.Analytics (hereinafter UA) are connected - Goals are configured in both services.
After a while, having strayed a bit from the TK, the programmers connected e-commerce for UA, but did it not through the dataLayer in GTM.
They returned the analytics counter to the site and connected the plugin via ga('require', 'ecommerce');
The question is which solution is correct, which is wrong?
1. Can I leave everything as it is - GTM with a duplicate of the analytics counter + goals and metrics?
2. Leave it as it is, but remove the duplicate UA counter in GTM - will there be any problems after this ecommerce?
3. Leave it as it is, but remove the duplicate UA counter on the site - will there be any problems after that in ecommerce?
4. Demolish all counters and transfer to GTM, and reconfigure e-commerce according to dataLayer.
5. Everything is wrong! Right like this..

Answer 1

4. Two identical counters on the page will distort the data, probably your bounce rate has already dropped to ± 10%, which indicates the presence of problems.
If the purchase data is transmitted via dataLayer, then you just need to create a tag with the UID of your UA account and enable this setting in the tag settings:
Make a couple of purchases on the site's test bench and see what the UA reports show you. Everything should be ok.