Changing Vertical Spacing After Heading (w. \linespread)

Question

For my paper, I need to use \linespread for linespacing. But I have such problem:

After seciton heading the vertical space is changing with respect to the size of the text after heading. Here I have 2 codes with different vertical size after heading:

\documentclass[a4paper,11pt,twoside]{article}
\linespread{1.4} 
\usepackage{geometry}
\geometry{a4paper,left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm} 
\usepackage{lipsum}
\begin{document}
  \section{HEADER}
  \lipsum[1-2]
\end{document}

And here with bigger size of text

\documentclass[a4paper,11pt,twoside]{article}
\linespread{1.4} 
\usepackage{geometry}
\geometry{a4paper,left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm} 
\usepackage{lipsum}
\begin{document}
  \section{HEADER}
  \lipsum[1-22]
\end{document}

without \linespread the vertical space is constant but with \linespread it changes based on the size of text. Is there any code to stabilize it ?

Note: I tried \setspace and \onehalfspacing instaed of \linespread . It effects similarly.

Thanks in advance for your help