Decrease in traffic since rebrand 6 months + ago

We rebranded and had a website overhaul 6 months + ago which included a change in theme. Ever since traffic and therefore sales has decreased considerably.
We waited 6 months ish for SEO to kick in as recommended and still no difference.
Via our old website we did achieve traffic and sales but wanted something more professional. We do feel this is a technical / behind the scenes issue. As far as I am aware the sitemap is connected and in the last month added the robot.text back into the theme. Mobile speed remains good.
We do have an SEO app called Booster SEO.

Any recommendations please? Thank you

sounds like a technical SEO issue from the rebrand

Hello there @ScentedAromas what’s the current situation as regards this? Have you been able to get an SEO manager to look through the updates and analyze the effects on your store? Have you also tried exploring other means of marketing such as social media and what not?

From what you said here, the changes made on your site are not recognized by Search Engines like Google properly. Have you tried to search your website in Google Search yet? This may give you some ideas whether updated contents have been indexed properly or not.

You can further check the feedback in Google Search Console and see if exist any issues on your end. By following the feedback in Google Search Console, things will be changed after waiting for some time.