i mean this is like the americans entering vietnam. You expect to fight a ragtag militia, and instead you find a competent fighting force forged in generations upon generations of hardship.
I'm no longer a soldier but if i were, Gaza is literally the last place i would want to enter. Urban hellscape, the bombings created makeshift shelters everywhere, and you have an enemy who's been preparing to fight you for decades and has a literal network of underground tunnels. There is literally no way to win this, the only way is to flatten the place from the air. Which is what israel is doing.
The biggest issue is that the French army, much like any other western army, has no experience in fighting peers. The only two countries in the world which have that are Russia and Ukraine. French officers themselves admitted that the russian army is not the main (arguably only) reference when it comes to peer-to-peer combat operations.
French troops would not fare any better than the élite, nato-equipped ukrainian brigades that smashed their heads against the Surovikin line.
I will say this tho - i never thought i would live to see german tanks burn on russian soil again, and i am sort of excited to see the french being beaten out of russia again