Samsung
Turn Auto Spacing On or Off auf Samsung
The Samsung Keyboard inserts a space automatically whenever you tap a suggested word from the predictive text bar or finish a swipe gesture in glide typing. This behavior is controlled by the Auto spacing option, which sits inside the keyboard's own typing settings rather than the general text input menu.
Auto spacing is stored per keyboard language. If you type in two or more languages, you need to open the setting separately for each one, since disabling it for one language does not change the behavior for another.
To adjust it, open Settings ➔ General management ➔ Samsung Keyboard settings ➔ More typing options ➔ Auto spacing, then turn the toggle on or off for the keyboard language you are editing.
Turning Auto spacing off helps when you regularly type compound words, hashtags, or usernames without a trailing space. Leave it on if you mostly type full sentences, since it speeds up typing right after each suggestion tap.
If words still run together after switching this off, check whether swipe typing or predictive text itself is causing the issue, rather than the spacing setting.