message-parser: underscores disappear in bold/bold-italic when in the middle

[mushroomgenie]

Description
When texts like this "ОЛ_1.2_2_00_ЭС", are entered in bold/bold-italic with underscored in between, the underscore disappears and the middle text is converted to italic.

Ran tests with this example and they are failing.

Steps to reproduce

Insert an image/gif

[Himanshu-kiran]

Yes,this issue is there.I am looking in this.