Showing ads to you is what pays for many streaming channels.
"No ads" is an extra cost subscription option available on SOME subscription channels. It involves purchasing a subscription to a higher "no ads" subscription tier for each such channel. Look for a "settings", "options", or similar option in each channel then look for an "upgrade", "remove ads", or other similarly worded choice.
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Roku Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X | Roku Streaming Stick 3600