The problem of restoring Z height after ToolChanger tool change

[wanwan]

I am debugging my ToolChanger。
I'm using the E3D configuration
（RRF3
.4）out of the box and I'm running into a problem that I can't solve. When changing tools, run tfree first, it will switch to relative mode to get out of bed, and then switch back to absolute mode. Then tpre will run, repeatedly switching to relative mode and lowering the bed, then switching back to absolute mode, during which time the bed is lowered a further 10mm, and finally tpost runs.
However, when the g-code resumed, the height of the bed did not return to normal.The tool hovers about 10mm above the print bed and prints in the air.
I have no problem printing with either tool individually, all offsets are properly calibrated and work fine
The slicers I'm using (S3D and pursaslicer) generate g-code and the next step after the tool change doesn't include Z coordinates, only XY coordinates, so I'm now confused which step is wrong?

[jay_s_uk]

@wanwan see the change notes for 3.4.0
After changing tool, RRF no longer moves the new tool head to the coordinates at which the old tool head was at when the Tn command was actioned. In most situations this should not matter, because GCode generators usually generate commands to move to the correct XYZ position after generating a Tn command. Usually, they restore XY before Z. However, Cura does it the other way round, which risks dragging the tool head across the print. Therefore when using Cura, or in any other situations in which you want to restore the old behaviour, we suggest you add command G1 R2 X0 Y0 Z2 Fxxx followed by G1 R2 Z0 Fxxx to the end of your tpost#.g files, if you don't already use those or similar commands.
https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x#:~:text=After changing tool,or similar commands.

[wanwan]

@jay_s_uk Omg, I overlooked important information. thanks