A person who probably doesn’t care about the issue but will say they support it in order to get popularity/recognition/etc. The only thing I can thing of is politician and campaign promises or hypocrite. But both don’t quite fit.
He never cared about the bees until it was trending, he’s such a/so _____. She is only started supporting the movement in order to get votes, after the election she’ll stop, all politicians are such a/so _____.
Awaiting further clarification, this sounds like virtue signaling. From Lexico:
virtue signalling (US virtue signaling)
The action or practice of publicly expressing opinions or sentiments intended to demonstrate one's good character or the moral correctness of one's position on a particular issue.
Example: "Standing on the sidelines saying how awful the situation is does nothing except massage your ego by virtue signalling."
The term implies that you don't have to care about the issue, but you can advertise that you do, and this will make you look like a concerned and upstanding citizen. Put a sticker on your window and pat yourself on the back; you support stuff. Cambridge online dictionary elaborates (ref):
Virtue signaling is the popular modern habit of indicating that one has virtue merely by expressing disgust or favor for certain political ideas or cultural happenings.
How about panderer? From Vocabulary.com:
A panderer is someone who tries to please others, not to help them but for an ulterior motive. A panderer kisses up to get something. A panderer is sometimes vulgar. Politicians are often panderers, especially the ones who say or do anything to get a vote or raise money. Pandering is dishonest because the panderer says what they think others want to hear, not what they really believe.
A term describing this behaviour is "self-interested"; another one is "self-serving.
(OALD self-interested considering only your own interests and not caring about things that would help other people
(OALD) self-serving interested only in gaining an advantage for yourself
-- He was a ruthless, self-serving politician.
-- This analysis could be said to be self-serving rather than accurate.
My favorite words for describing such people with these characteristics are:
(MW) unctuous: "having, revealing, or marked by a smug, ingratiating, and false earnestness or spirituality"
(MW) disingenuous: "lacking in candor; giving a false appearance of simple frankness"
(MW) facile: (1c) "readily manifested and often lacking sincerity or depth"
(dictionary.com) slacktivist: A person who says they support a cause but does little or nothing to support that cause
(MW) histrionic: "deliberately affected; overly dramatic or emotional"
(MW synonym discussion) "THEATRICAL [sic] implies a crude appeal through artificiality or exaggeration in gesture or vocal expression."
In a more clinical sense, Histrionic Personality Disorder (HPD) is a disorder afflicting people having symptoms including overly-enthusiastic attention-seeking behavior; sometimes HPD shares comorbidity with Narcissistic Personality Disorder (NPD). (springer.com)
