Unknown Tabs, Tab Group showing up

iPhone X 16.7.10

MacBook Air (M1) Sequoia 15.3.2

Yesterday, I noticed a bunch of tabs opened in my default tab group that I don't remember opening (all of them were fosdem.org). I closed them and forgot about it for a while. In the evening I found a tab group "Home Decoration" with 2 tabs, Google Search (which I never use) and a website I've never seen with an article on home decoration. This was on my iPhone.

I checked my devices list and no unknown devices were there. I suspect my account was compromised somehow and changed my password.

I cannot remember opening the fosdem.org tabs (but they were somehow related to things I've searched in the past). Maybe I tapped on something while browsing and that opened several tabs? Maybe my daughter clicked the links while I left my phone unattended? That I can somehow understand, but creating a Tab Group called "Home Decoration" with a tab on Google search and website I've never visited before is what baffles me more (my daughter is 2 years old).

I had one TestFlight extension in Safari (Mac) which is an ad blocker. Maybe it is related? I deleted it just in case.

Is it there an "accidental" way a Tab Group can be created? Does the above look more like malware?