Learn English – First conditional only for future tense

I think the difference between the two types of examples that you've exhibited is the relative placement in time of the action in the "if" clause, and the action in the other clause.

• If it rains in the evening, we won't go for a walk - here, the event of raining occurs BEFORE the decision about whether to go for a walk.
• My teeth will rot if I eat too much sugar - presumably, I'll be eating the sugar BEFORE my teeth rot.
• If it will significantly increase complexity, don't implement this feature - here, the increasing of complexity occurs AFTER the implementation of the feature.
• I will give you money if it will make you happier - here, you becoming happier occurs AFTER I give you the money.

In all the cases where the "if" part happens first chronologically, we use the present tense. In the cases where the "if" part happens second, we use the future tense. However, because sentences of the first type are far more common than sentences in the second type, a good rule for learners to adopt is "don't use the future tense with IF".

If-clauses that predict the future are commonly followed by a main clause with will + infinitive:

If you ask without any background, many people will assume you are just too lazy ... .

What complicates the present example is the use of the word likely. This word already has a future implication so there is no need to use will too. For example:

He is likely to be late = It is probable that he will be late.

For this reason the first of the OP's sentence is perfectly acceptable.