I've been a player and DM for about 11 years. We are all older player between 45-55. Last night a Mummy Lord had us on the ropes. He had already killed out NPC companion. We escaped up a tunnel using a scroll of arcane gate and tried to use Rope Trick to hide. But the last guy in didn't pull up the rope so the mummy know exactly where we were.
We were in bad shape. We were trying to go over our spells and resources and we didn't come up with much. I proposed that I hold him off while the druid wild shapes into something fast and runs for it with the warlock using my boots of speed to follow him at full pace. I was looking forward to going down heroically to save my comrades. Or at least fighting for 2 rounds and then trying to escape myself. The problem was existential to our characters. And it was super fun.
Then DM just has the mummy lord laugh at us and walk away. He placed a spirit guardian at the doorway to his lair (Not underneath out rope). And just let us leave go for no apparent reason.
It was so anticlimactic. It just took the wind right out of my sails. Why raise the stakes to that level and just let the players walk away to (presumably) take a long rest? Just finish the scene. What are the stakes even for if you are just going to handwave the results of poor strategy and execution?
Anyway if you are a DM and your players are in a bad way, just follow through. Don't underestimate them and don't rob them of opportunities for bravery.