Yes I have been through this and multiple variations of this.
Mostly positive results particularly in terms of team ownership of quality and quality assurance rather than a separate group.
Some people argue independent test is better, in my experience that’s meh, testers on the team just need think independently at times to get the same result.
I recommend maintaining an autonomous test guild which is about learning, knowledge sharing and craftmanship. Testing is a deep skill area and still needs developing rather than a generalist role.
Shift automation ownership to team with developers taking the lead was one of the most positive steps of combining the teams, testers available to assist but it was not an afterthought.
Rethink what testing is all about, with joint team ownership you can test ideas and designs at the start of the project, propose A/B test hypothises that allow team experimentation, encourage better testability, push for better analytics features to be built in etc etc. The key things are that these are all team things that when the testers are separate its almost futile to drive improvement.
Consider increasing the developers testing skills and perhaps transition the testers over time into more of a coaching role, this helps with the team ownership of quality.
Similarly its a great opportunity to pair with developers building more technical skills. You may also find that your good automators can transition into product coders who can also automate which is ideal.
Because its one team, any blame game crap should also diminish.
Okay so most of the above is maybe best case scenario, so of these transitions just go haywire.
Testers seen as owned by dev lead who gives them work that nobody else wants, i.e they lose their authority.
Good exploratory testers forced to do average automation in the name of team utilisation.
The team tries to maintain the status quo but under a new structure so nothing improves apart from a reduced sense of value.
One other side effect I have seen was that the need for as many testers as we had reduced, that can be scary but it was fairly natural in my view. Tended to end up in the long run with fewer but more capable testers with some coaching skills.