Like many spouses on Sunday, the Marvel star took to Instagram to pay tribute to the moms in his life ... writing a glowing tribute for his wife Katherine Schwarzenegger and mom Kathy Pratt. Of course, he also has a kid with Anna ... his 11-year-old son Jack.

While Chris had a mouthful for his current wife, he made no mention of Anna -- BTW, he did this last year, failing to shout her out at the time -- and some people were pissed.

Tons of followers of his flooded his comment section, asking why he wasn't highlighting Anna -- pointing out she was still the mother of his child ... and worthy of recognition on the holiday.

However, in the same breath ... many of Chris' other fans have since come to his defense -- noting it'd be weird of him to give kudos to his ex-wife ... especially since he didn't pay tribute to her last year. Also, they don't seem to be all that friendly post-divorce.

One fan commented ... "Every year you guys are so obsessed with talk about his ex-wife when he has remarried. I'm sure Anna doesn't want him calling her out either."

Another chimed in ... "Y'all, as an ex-wife, not all of us want some public post from our ex. And as a current wife, I wouldn't want my husband posting one. No need to slam the guy."

A third added ... "This man does not have to shout out his EX wife on mother's day. That is so weird."

Chris has been in the hot seat a number of times for his IG tributes. Remember, the internet dragged him in '21 when he thanked Katherine for giving birth to "a beautiful, healthy daughter," as fans assumed it was a dig at Anna -- who had welcomed their son Jack prematurely in 2014.

A year later, Chris admitted he broke down in tears over the concocted drama, telling Men's Health ... "And I’m like, that is f***ed up. My son’s gonna read that one day. He’s nine. And it’s etched in digital stone."