He still likes his ex’s pictures. Should I be worried?

Let me preface this by saying I hate social media.

I just got back into the dating world after taking some time to work on myself after some crappy dating experiences. I’m pretty rusty after all this time.

A good friend of mine set me up with her SO’s buddy. We met about 1.5 months ago. We seem to be hitting it off. The issue is, upon finding out, my friend told me he likes about every other picture his ex has posted. They broke up in early October. I do know she broke up with him and shortly tried to reconcile, he said no, but then later told her he was struggling with the breakup and she said she was too. This happened in October. Also, they had also discussed marriage.

I’m trying to tell myself it’s just him liking the content. He’ll like his other ex’s pictures too, but she’s from years ago. He’ll even like pictures of old flings that didn’t work out, so maybe he’s just weird?

Either way should I be worried? I’m fairly interested, but it’s more so I just don’t want to get burned again. I just don’t want to potentially invest in something down the line if there may be a red flag...

So apparently after he turned her away he was blowing up her phone saying stuff like the breakup really messed with him, how he wanted to stay but couldn’t. Then a little later the I’m having a hard time message followed. Also, my friend is under the impression that he tried to make her jealous (I don’t agree). He snapped a video of his food and then showed the girl he was on a date then posted it on social media. This was a few weeks after telling her that he was struggling. Not quite sure showing off your date on social media means you're trying to make someone jealous though.

Anyway, she said she was hurt but loved him enough to be happy for him to be moving on. He replied with a question mark, and she said your video that you posted. He told her how he loved her very much but they just argued a lot. Then sent her another message saying it’s not wise to give out information about what may or may not be going on his dating life. She said she wasn’t asking but wished him all the best. He then liked her picture a few days later and I was told he was looking at her social media. This happened in November. He’s still liking her stuff now.