Disclaimer: I recommend using the original TPU spacer linked below. This has a little bit more protrusion to the front and may snag on to your display cable (for example when homing the print head) Before running a print check that the installed spacer does not scratch or touch the display cable in the front right corner(reference photo added). Best way to know is to move the print head manually to the corner and see underneath if the cable needs to be moved and/or adjusted.

This a mod of the original spacer posted here:

https://www.crealitycloud.com/model-detail/680a44f3f8576ee3f9e5ec07

This mod was created for better ease-of-use to handle the tiny insert part as some user suggested it may be difficult to insert/remove it. It has a folding side that will fold to the side and click in place to prevent it from moving during printing when the print head is moving at fast speeds.
6 spacers from 0.4 to 1.2mm thickness to loosen the extruder spring on the K2 Plus when printing with TPU filaments. Recommended to print in PETG, ASA or ABS due to being close to the hotend.
Easy to install. Just pull the extruder tab to the right and in the open cavity insert the needed the spacer. This spacer is designed to fit next to the PTFE tube pneumatic connector from the Creality wiki:

https://wiki.creality.com/en/k2-flagship-series/k2-plus/secure-PTFE-tube

K2 Plus Extruder tensioner for TPU Mod Side Folding #1

0.2mm layer, 2 walls, 100% infill

0.2mm layer, 2 walls, 100% infill

0.2mm layer, 2 walls, 15% infill