There must be an issue with your installations. The contextual clipboard icon at the lower left corner of the pasted content is showing here in both PowerPoint 2016 (16.16.6) and 2019(16.21).
As a workaround, if you click on the down-pointing arrowhead on the right side of the Paste button, you can choose Keep Source Formatting:
You can also add the command to your Quick Access Toolbar for single-click access:
- Click on the down-pointing arrowhead at the right end of the QAT and choose More Commands....
- Change Choose commands from: to All Commands.
- Scroll down to Paste and Keep Source Formatting and select it.
- Click on the right-pointing arrowhead button between the 2 lists. The command is added to the right-hand list.
- Choose Save. The command is added to the right end of the QAT.