What does this mean?
It appears that an input is using type="tel" when it is not asking for a telephone number.
This is normally done to have a touch-screen device present a number keypad to the user instead of the standard keyboard.
For example:
<label for="cc">Card number</label>
<input type="tel" id="cc">
This used to be seen especially on date fields within government services.
Impact on users
Typically this doesn't have any impact on a user (beyond not being semantically correct), but is often a sign that a better solution is not being used.
How to fix
If the field is asking for a non-telephone input, then look at using inputmode instead as this will direct the browser to present the correct keyboard to the user. The best match normally be inputmode="numeric". Avoid using inputmode="decimal" as this can prevent users entering the correct data.
For example:
<label for="cc">Card number</label>
<input type="text" id="cc" inputmode="numeric">